The new bun is similar to the brioche bun that it replaces and can also be found on Jack's sirloin burgers as well as the Homestyle Ranch Chicken Club. In a marked departure from most fast food buns, the signature bun came well-toasted on both sides. Picking it up, there's a satisfying crisp, thin crust to it that reminded me of fresh-baked bread and is something I haven't really ever encountered in a burger (fast food or otherwise). Inside was a squishy soft, moist, and sweet crumb that's very brioche-like. If you liked the previous (and short-lived) brioche bun, this one is even better.

The beef patty was moist, thick and had a seasoned flavor similar to Jack's sirloin burger patty (while I was told by a Jack in the Box rep that the Buttery Jack burgers do not displace any current burger on the menu, the similar flavors make the sirloin burgers a bit redundant). Importantly, the patty actually fits the width of the bun with a sort of square-ish shape like what's offered at Wendy's. The beef's seasoning added pretty enjoyable flavor that's enhanced by the wonderfully buttery and garlicky herb butter. It's actual butter rather than a "buttery" spread. The "herb" portion didn't really come across though.

The green leaf lettuce adds a premium touch, while still offering a little bit of the crispness of iceberg lettuce. Both it and the tomatoes were fairly fresh (the tomatoes were just a little green and unripened though).

The provolone proffered a very mild creaminess.

The creamy tomato sauce tasted like slightly roasted tomato and mayo.

Overall, Jack in the Box's Classic Buttery Jack is an excellent and top-notch burger that sets itself apart from what's currently in the market. Additionally, it's well thought-out and well executed. I'd put it above similar premium burgers at major competitors like McDonald's and Wendy's. It's early in the year but if I have a better new fast food burger this year, I'll be surprised (then again, I haven't yet tried the Bacon & Swiss version of the burger).